Berkeley police announced today a man was arrested last week on suspicion of posing as an undercover police officer and sexually assaulting a woman in April.Jerry Brown Jr., a 42-year-old El Sobrante man, allegedly picked up a 27-year-old woman in the area of San Pablo Avenue and Carrison Street in southwest Berkeley on April 4. Police say he told the woman he was a Berkeley police officer, drove her around and showed her an “official looking” badge. Brown then allegedly told the woman he had a firearm, stopped his truck in the 700 block of Heinz Street and sexually assaulted her multiple times, police said.Police said a break in the case came when a community member provided a license plate to the 1996 Ford Ranger.Berkeley police arrested Brown at his El Sobrante home on Wednesday and he was charged Friday with false imprisonment, oral copulation and sodomy, according to police. He was later released on bond.